Method of producing light.



No. 781,605. PATENTED JAN. 31, 1905. P. U. HEWITT.

METHOD OF PRODUCING LIGHT.

APPLICATION FILED JULY 1, 1904.

MW flax F ATTORNEY Patented January 31, 1905.

iJNiTEn STATES ATENT OFFICE.

PETER COOPER HIUYITT, OF NEiV YORK, N. Y., ASSIUNOR TO COOPER Hl llVlTT ELECTRIC COMPANY, OF NE\\' YORK, Y., A CORPORATION OF NEW YORK.

METHOD OF PRODUCING LIGHT.

SPECIFIK ATION forming part of Letters Patent No. 781,605, dated January 31, 1905.

Original application filed April 25, 1902, Serial No. 104,607. Divided and this application filed July 1,1904. Serial No. 214,901.

To Ir/mnr it may conic/7'11;

Be it known that l, Patna Coornn ll nwi'r'r, a citizen of the United States, and a resident of New York. county of New York, State of New York, have invented certain new and useful lmprovements in Methods of Producing Light, of which the followingisaspeciiication.

l have found that when an inclosed gas or vapor of suitable character and density contained within a holder of suitable character and dimensions and having appropriate electrodes is connected in an electric circuit there will be opposed to the passage of electric cu 1'- rent an initial resistance, which may be overcome by an electromotive force of sutiicient value, the gas or vapor then serving as a conductor across the gap in the metallic circuit when the proper conditions of current are supplied. This initial resistance appears as a self-created electrical-resistance phenomenon at the negative electrode, which on being overcome removes itself without any appreciable energy loss. The resistance which the gas or vapor shall offer to the current during the period of discharge may be made of practically any desired value within wide limits,

can also be made of any desired value, each independently of the other. In other words, it is possible to so construct an apparatus of this sort as to present initially a very high may be kept at their normal value by maintaining a constant temperature of the inclosed gas or vapor. The means for maintaining such a temperature, as well as the means for controlling and determining the other factors hereinbcfore mentioned, are fully set forth in certain patents issued to me on the 17th day ofbeptember, 1901. Ifdesired, special means for maintaining a constant temperature may be applied to the apparatus when it is used in place of a spark-gap. Inasmuch as the electrodes remain practically unchanged by repeated use and the whole apparatus is sulr stantially unaltered, a single apparatus will operate Without any need of attention or repair. Should it be desired to provide a higher initial resistance, so as. to increase the rise of potential in the discharge-circuit, a new apparatus can be substituted calling for such higher potential at the start; but this new apparatus may, like the lirst, consume little or no current during the discharge period. These electric circuit-ln'eakers may be used in series or parallel, and in case it is not desired to have the initial resistance to starting 1 so great it may be modified by starting bands while the initial resistance above referred to resistance to the passage of the current and i to present a very low resistance to the current 1 after it has once been established through the apparatus. Should other conditions be reuired, both these factors may be varied by altering the construction of the apparatus in the first instance. Assuming, however, a low resistance. during the discharge period and a desired initial resistance, the amount of work done in the vapor-gap is practically very small. ;\cc(. rdingly an apparatus of the kind described can be ecomnnically used in place of a spark-gap, possessing. by reason of the features above mentioned, a very great advantage over the ordinary air-gap and a still greater advantage over a 'ehnelt interrupter. The described factors having once been fixed at the electrodes, as described in my patents, and in case it is desired to operate several breakers in parallel they may be timed by connecting the starting bands or groups thereof together. In these respects the described apparatus is superior to the ordinary air-gap, in using which it is necessary to keep the terminals of the conductors or balls smooth and polished and in which any increase in the initial resistance (as by the separation of the balls or conductors) also entails an increase of resistance during the period of discharge, and, further, the resistance during the discharge period may be lower and is far better than a \Vehnelt interrupter on account of the great loss of energy in the \Vehnelt interrupter.

Another feature of my apparatus is that the gas between the electrodes acts as a true vapor-conductor after the circuit is once established through the vapor, and when this conductor is made of very low resistance practically a short circuit formed. Since the vapor-resistance factors are known and the conditions they are subject to, the action can always be depended upon. By the passage of current the electrical pressure or voltage is lowered to a point where the resistance to starting re-forms, whereupon the checked current rebuilds or reestablishes itself, its electrical pressure rising until the breaking-down pressure is again attained, after which the same succession of actions is repeated.

By utilizing the described apparatus in the manner indicated periodic currents of high frequency can be produced by reason of the fact that its action is very quick and uniform. It is especially adapted to the Work of creating currents of definite time periods and rapid alternations. I have found, for instance, that with a device consisting of an inclosed mercury vapor organized in the manner described in my patents above referred to and provided with a condenser and a reactive device suitably placed and adjusted with reference thereto it is possible to produce such currents, the action being in the first instance to apply to the terminals of the vapor-gap a potential difference sufficient to overcome the initial resistance, whereupon a rapid fall of potential takes place until it reaches a point where it is insufficient to overcome the reduced resistance at the vapor-gap. At this point the current ceases to flow, the break in current-flow being abrupt on account of the immediate reestablishment of the initial resistance of the vapor. Thereafter the applied potential rises until it reaches the breaking-down pressure of the initial resistance and then the same cycle of operations is repeated.

The intermittent or vibratory currents produced in the circuit by the circuit-breaker thus described may be applied to use in the vapor or gas gap itself, or they may be applied to other apparatus, or to both simultaneously. For example, one application of the present invention would be to serve the purpose of furnishing a periodic current for wireless telegraphy and another for producing rapidly-varying currents for the purpose of producing light by induction, and still another application would be that of producing light, say, in the vapor-gap itself, by means of successive electrical impulses of relatively high electromotive force, causing a high illumination of the vapor or gas at such rapid intervals that the physiological impression is that of continuous illumination. In making the last-named application of my invention I cause the intermittent currents produced by the intermittent action of my apparatus to act upon the vapor in the gap in such a way as to produce a brilliant light. To this end the density of the vapor and the dimensions of the container are suitably proportioned to each other for this purpose, as set forth in a general way in my patents of September 17, 1901; but whereas in the inventions set forth in the said patents the vapor is intended to be affected by a flow of current of given value at a certain potential the purpose in the present instance is to afiect the gas or vapor by an intermittent How of a current of practically the same value, but of higher potential, the energy represented by the intervals between the impulses being intermittently withdrawn from action and reappearing in the form of an increased quantity in the rapid periodic currents. The resultis an increased brilliancy on the part of the lamp, due to this increased consumption of energy per unit of time, While the efiect upon the eye becomes that of a light due to a continuous flow of current of greater quantity.

In the accompanying drawings, illustrating an application of my invention, Figure 1 is a diagram showing a general organization of the apparatus. Fig. 2 shows a modification, and Fig. 3 is a theoretical diagram.

Referring to the drawings, 1 represents any convenient source of electrical energy say, for instance, a continuous-current generator, (which for convenience it may be assumed in this particular instance to be of three thousand five hundred volts.)

2 and 3 represent main conductors leading from the generator.

4 represents an electric device of the character described in my patents hereinbefore referred to. This is connected at any convenient point between the conductors 2 and 3. A condenser 5 or other suitable device or means for affording an electrical capacity is connected across the terminals of the device 4. An inductive resistance 6 is connected in the line 2 between one plate 7 of the condenser 5 and the source 1 of current. It is to be un- G derstood that by referring toa condenser I mean to include other suitable means for securing the requisite electrical capacity.

Assuming that the circuit of the generator is closed by the switches 9 and 10, there will be a sudden rush of current through the lines 2 and 3, tending to charge the plates 77 of the condenser 5. The inductive resistance 6 opposes a counter electromotive force to the applied electromotive force, thus temporarily resisting the flow of current beyond that resistance. The condenser 5 thus becomes gradually charged as the electromotive force at its terminals rises. Assuming that the device 4 will be traversed by a current under the influence of a difference of potential of three thousand five hundred volts, then as soon as the condenser 5 has attained its charge a current Will traverse the device; but the moment such current does traverse the device the difference of potential at its terminal is enormously reduced. Practically it may be made to drop as low as one hundred volts or even below twenty volts. Thereupon the condenser 5 discharges or feeds the circuit be- The reactive COll tween itself and the device.

(3 may serve to prevent at this time too great a discharge fromthe source of current. On the discharge of the condenser the passage of current through the device will cease and the operation be repeated, causing I'ZIPlCllX'SLlC' ceeding impulses of current to traverse the device. Each succeeding impulse will be at a potential of, say, three thousand five hundred volts, and the light emitted by the device will be of abrilliancy due to the product of the average voltage into the current during the successive time intervals of currentflow.

It is characteristic of these devices that they may be constructed not to pass an appreciable amount of current below a given voltage, which can be predetermined, and therefore at the end of certain definite periods the current ceases to pass. Accordingly the device has a delinite consumption period between the extreme higher limit of applied electromotive force and the lowest limit at which the device will take current. \Yhat is perceptible to the eye are the luminous vibrations due to these successive passages of current, the intervals of no current being undiscernible by reason of the rapidity with which the intervals follow each other. It is also characteristic of apparatus of this type, whether used as a lamp or as a discharge-gap, that it may be so dimensioned with relation to the vapor column that the heat radiation will be equal to the heat absorbed under ordinary conditions that is to say, the temperature may be maintained constant, thus securing constant density in the gas or vapor. The enlargement represented by the chamber H at the top of the devices l in Figs. .1 and 2 is usually employed as contributing to the maintenance of stable temperature and density.

lt may sometimes be found desirable to make use of additional means for carryingolf the heat absorbed. Such means may, for ex ample, consist of a water-jacket outside the body of the apparatus.

The period of the condenser discharge may be further retarded by an inductance device placed in the condenser-circuit. An additional condenser 12, placed between the source and the condcnserj. may serve to assist the speed of charge and discharge through the inductance b. A similar inductance 6 may be included in the branch 3, it'desired.

In my devices the starting 1s usually facilitated by the use of a band 14, placed in the i neighborhood of the negative electrode upon the exterior of the device and connected by a conductor 15 with the positive electrode or the conductor leading thereto and is useful where lower initial voltages are to be used. The action of this band may be that of producing an electric strain at or near the negative elec trode, such strain tending toward causing a discharge to pass between the electrodes. In

any case it is found that the presence of a starting-band in the position indicated in the drawings makes it possible to start the apparatus by the application of a lower electromotive force than would be the case if the band or some equivalent thereof were not present.

By inserting the primary coil 16 of a converter 17 in one of the conductors-for instance, 3, as shown in Fig. 1--an alternating current may be produced in a secondary circuit 18. which in turn may be used for any desired purpose. The primary coil 16 in this case may be utilized as the inductance device referred to above for retarding the period of the condenser-circuit. In Fig. 2 I show the primary 16 of the converter 17 connected up between two condensers 6 and 20, connected in series across the terminals of the device In Fig. 31 have shown in diagram the theoretical curve illustrative of the differences of potential and the changes therein which may occur in a circuit such as shown in Fig. 2. hen the circuit is closed, there is a rise of potential at the terminals of the device from zero to three thousand live hundred volts, as shown by the portion 0 of the curve. Thereupon current traversing the device, the condenser discharges, dropping the current to one hundred volts, as indicated by the portion 7) of the curve. The voltage then again rises to three thousand live hundred volts, as indicated by the portion of the curve, the rate o'fcharging being depemlent upon the amount of self-induction or resistance in the circuit between the condenser and the source. By

varying this self-induction, the portion 1/ of the curve may be made more or less abrupt, and by varying the inductive capacity of the circuit between the condenser and the device the portion 7) of the curve representing the operation of the device may be more or less prolonged. The lines drawn above and below the zero-line near the end of Fig. 3 are designed to illustrate the gradually-dccreasing surgings of the condenser-current during the interval of discharge in its circuit. By properly adjusting the capacity of the condenser, the circuit, and also the inductance almost any required definite period of charge and discharge may be secured. The frequency of the discharge from the condenser 5 may be determined either by its own natural period of oscillation or governed by the charge which the condenser receives from the line as controlled by the line.

The currents developed in the circuit and hereinbet'ore described as utilized for increasing the luminosity of one of my lamps may in addition be used for other purposes, or the quality of my apparatus as a light-giving body may be fully subservient to the development of currents for other purposes. In other words, I may in some instance construct a gas or vapor apparatus having the primary object of controlling the rate of currents developed in the system, which currents may or may not operate to give lightin the apparatus.

In distinction from the ordinary airgap conditions under which the vapor constituting the path is placed make it possible to predetermine and control the voltage required to break down the resistance of the gap, which always remains the same in any given apparatus under the same conditions. The apparatus can be so constructed that the loss of energy during the passage of the discharge will be practically negligiblethat is to say, the medium through which the discharge passes may be of such high conductivity that no material waste of energy will take place in the operation of the device. By virtue of the same quality the apparatus imposes no material limitation upon the natural number of useful oscillations of the circuit. These features, which render the apparatus controllable, avoid the suppression of useful oscillations, prevent waste of energy, and render the resistance of the device independent of the current flowing after the initial resistance has been overcome, are among the features which differentiate the present apparatus from what is usually known as the v 7 spark-gap or air-gap. A further driferentiation is that the device when constructed with high conductivity operates without developing inertia characteristiCs-that is to say, the initial high resistance is immediately reconstructed as soon as a discharge passes, whereas there is no such sudden cessation of action when an air-gap is traversed by a discharge.

It is incidental to the character of my apparatus that I am at liberty to construct the electrodes either of volatile or non-volatile material. The electrode material may conveniently be a conducting liquid, in which case the electrode will present a clean liquid surface. and in case the liquid is volatile the elec trode will possess the property of never becoming heated beyond the boiling-point of the liquid. Such material as volatilizes from the electrode may be condensed, say, in the cooling-chamber 44: and in returning in the condensed state to the electrode will unite with the latter, thus replacing the loss due to vaporization.

The intensity of certain characteristic electrode phenomena may be increased or diminished by devices external to the electrode, such as the action of the starting-band or the effects of temperature on the electrode.

l l l In the parent application, filed April 25, 1902, Serial No. 10 L607, of which this application is a division, claims are made, broadly, upon certain methods of operation disclosed herein. 7 Also in a companion application, Serial No. 104,608, filed April 25, 1902, claims are made upon certain features of the apparatus herein described, and in another application which is a division thereof, Serial No. 124,624, filed September 24:, 1902, claims are made upon certain other features described herein.

1 claim as my invention 1. The method of producing light through the instrumentality of electric energy traversing a conducting gas or vapor, which consists in causing energy from a source of electric potential of a given value to be applied to the terminals of the gas or vapor path in successive electrical impulses varying in potential from a value above the normal resisting power of the vapor-path to a potential insufiicient to cause a continuance of the flow of current therethrough.

2. The method of transforming electrical energy into light through the medium of a light-giving body or material which has a high initial resistance and possesses the quality of taking no current below a definite low limit of electromotive force, which consists in periodically breaking down the initial high resistance through the medium of a source of high electromotive force, and during each period choking down the potential applied to the translating device to or below the extreme low operative limit by devices entirely independent of the translating device, and recharging the source of high electromotive force.

3. The method of transforming electrical energy into light by means of a light-giving body or material which has a high initial resistance and possesses the quality of taking no current below a definite low limit of electromotive force, which consists in periodically breaking down the initial high resistance by means of a source of high electromotive force, and during each period choking down the potential applied to the translating device to or below the extreme operative limit by devices entirely independent of the translating device.

4:. The method of producing light through the instrumentality of electric energy traversing an inclosed gas or vapor having the quality of opposing an initial resistance which can be broken down by a given difierence of potential and of conducting electrical energy under the influence of a lower potential, and of reconstructing its initial resistance at a predetermined lower potential, which consists in periodically applying a potential of sufficient value to cause an initial flow of current succeeded by a flow under the influence of a lower potential, thereupon causing such a drop of IOC IIC

potential as to fall below the value required to continue the tlow, and repeating these operations.

The method ot'obtaining light from a suit able source which consists in discontinuously producing a comparatively high intensity of illumination in a light-giving substance, the intervals being so short as not to interfere with the purposes for which the lamp is to be employed. the time period of response of said substance to the energizing force being small as compared with said intervals, and the duration of the variations being in part determined or controlled by a characteristic or condition of said substance.

6. The method of obtaining light from a suitable source, which consists in intermittently operating the light-giving medium at an abnormally high etliciency, the intervals being such as not to interfere with the purposes for which the lamp is to be employed, the time period of response of said medium to the energizing t'orce being small as compared with 5 said intervals, and the duration of the variations being in part determined or controlled by a characteristic or condition of said medium.

T. The method of obtaining an average illumination from a suitable source, which consists in discontinuously bringing the lightgiving medium to a high intensity whereby compensation is made for the periods of no illumination, the intervals being such as not to interfere with the purposes for which the lamp is to be employed, the time period of response of said medium to the energizing 't'orce being small as compared with said intervals, and the duration of the variations being in part determined or controlled by a characteristic or condition of said medium.

Signed at New York, in the county of New York and State of New York, this Qlth day of June. A. D. 190i.

PETE H COUPE R HE W lT'l.

\Vitnesses:

\V'M. H. UAPEL, GEORGE H. S'IOCKBRIDUE. 

